function draw() {
   var canvas = document.getElementById("canvas");
   if (canvas.getContext) {
      var ctx = canvas.getContext("2d");
      ctx.fillStyle = "rgb(200,0,0)";
      ctx.fillRect (10, 10, 55, 50);
      ctx.fillStyle = "rgba(0, 0, 200, 0.5)";
      ctx.fillRect (30, 30, 55, 50);

      ctx.strokeRect(0, 0, 150, 150);

      ctx.fillStyle = "rgba(0, 100, 100, 0.5)";
      ctx.fillRect (125, 125, 170, 170);
   }
   else
   	alert("I don't handle your browser!");
}
